The invention relates to an arrangement for false-twist spinning having a drafting unit, having a false-twisting device which follows, having a connecting withdrawal device, and having a drivable rotation element which is connected in front of the false-twisting device and which is provided with an air-permeable shell surface. The air permeable shell surface is subjected from the interior to suction by means of a suction device having a suction slot. The axis of rotation of the rotation element is directed essentially perpendicularly with respect to a plane extending through a nip line of a pair of delivery rollers of the drafting unit.
In a known arrangement of the initially mentioned type disclosed in German Patent Document DE-A 37 14 212, two rotation bodies are provided, the yarn travelling between them. The yarn is alternately pulled to these rotation bodies promoting the spreading-away of fibers from the fiber core.
It is an object of the invention to provide an arrangement of the initially mentioned type in which the spreading-away is further improved, and the winding of the spread-away fibers around the yarn core is improved still further.
This object is achieved in that the rotation body is arranged directly behind the pair of delivery rollers in such a manner that the suction device is effective into the area of the nip line, and that the suction slot has a section which extends essentially in the direction of the nip line and which is situated in the area of a deflection of the sliver leaving the pair of delivery rollers located in front of this section.
By means of this construction, it is achieved that a spreading-away of fiber ends is already obtained in the area in which the sliver has the smallest twist and thus the spreading-away can be carried out most effectively.
In a development of the invention, it is provided that the sliver leaving the pair of delivery rollers is unguided in the area of the deflection. This ensures that the spreading-away of the fiber ends is not impaired by mechanical guides, for example, resting against one of the roller surfaces of the pair of delivery rollers.
In a further development of the invention, it is provided that the rotation body is designed as a narrow roller which, by means of its circumference, projects into a wedge-shaped gap formed by the pair of delivery rollers. As a result, it becomes possible to move the shell surface of the rotation body very close to the nip line of the pair of delivery rollers. The pair of delivery rollers will then serve as an air guiding device in the area of the nip line by means of which an advantageous targeted air current is obtained which promotes the spreading-away of fiber ends.
In a further development of the invention, it is provided that the shell surface of the rotation body is driven to a circumferential speed which is higher than the delivery speed of the pair of delivery rollers and the withdrawal speed of the withdrawal device. The shell surface of the rotation body therefore moves faster than the sliver. As a result, it is achieved that the spreadaway fiber ends are moved faster than the yarn core, in which case, the fiber ends are, on the one hand, placed against the yarn core and, on the other hand, are wound around the yarn core by means of an ascent that can be determined by way of the circumferential speed of the shell surface of the rotation body, the yarn core rotating around its axis as a result of the false twist introduced by the false-twisting device and in the process sliding on the shell surface of the rotation body.
In a further development of the invention, it is provided that the rotation body is driven by means of a driving element which also drives the rotation bodies of several adjacent spinning points of a machine. Because of the axial direction of the rotation body, it is possible to provide a tangential belt extending through in the longitudinal direction of the machine for the drive of the rotation bodies.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.